1. Field of the Invention
The present invention relates to hydraulic pump assemblies. In particular, the invention relates to a hydraulic pump unit that may be retrofitted to or provided on an all-terrain vehicle (ATV).
2. Description of Related Art
Various ATVs have been designed primarily for sports and leisure riding. Typically, such ATVs include a frame and an engine mounted on the frame to power the wheels and propel the ATV. The frame may have three or more wheels operatively couple thereto.
In recent years, there has been a desire to use such ATVs for work-related purposes such as lawn-mowing, snow removal, or forestry. To convert ATVs into work vehicles, various accessories (for example snow blowers, snow plows, lawn mowers, log splitters, etc.) have been designed for attachment to such ATVs and are presently available. Unfortunately, these accessories have a significant drawback in that two engines, one for propelling the vehicle and one for driving the accessory, are generally required, thus making such systems expensive. For example, U.S. Pat. No. 6,178,668 discloses a snow blower accessory that utilizes a first engine to power the vehicle and a second engine to power the snow blower.
To eliminate the need for a second engine, various mechanisms have also been developed that use the ATV""s engine to both propel the vehicle and power the accessory.
U.S. Pat. No. 4,577,712 discloses a hydraulic pump assembly that connects to the ATV""s engine to provide hydraulic power for accessories. The hydraulic pump is mounted to the ATV""s frame forward of the ATV""s engine. Rotation is transferred from the crankshaft through the ATV""s centrifugal clutch and then to a manually operable hydraulic pump clutch. The rotational output of the hydraulic pump clutch is then transferred via a chain drive to the input shaft of the hydraulic pump. The hydraulic fluid discharged under pressure by the hydraulic pump then flows through a hydraulic circuit to power the hydraulic motor of an accessory such as a lawn mower. Because of the complexity of the hydraulic clutch and chain drive system, the disclosed hydraulic pump assembly is expensive, and requires significant modification of the ATV. The modifications generally relate to the engine, e.g., an extra shaft and clutch are required and holes must be provided in the engine case of the ATV for the chain. Additionally, the hydraulic clutch cannot draw maximum available power from the engine.
Canadian laid open Patent Application No. 2,197,054 (the ""054 application) discloses another way of using the existing engine of an ATV to drive a hydraulic pump assembly to power an accessory. ATVs typically have auxiliary starter units (e.g., hand pull starters) that mount directly to the engine""s crankshaft. The hydraulic pump assembly disclosed in the ""054 application is mounted to the engine within an auxiliary starter casing in place of the auxiliary starter recoil. The input shaft of the hydraulic pump is generally coaxial with the crankshaft of the engine. The pump assembly uses a joint mechanism, e.g., a polymeric joint, in which the pump""s input shaft engages the crankshaft of the engine. However, because the joint members are carried on separate shafts, for example, each is cantilevered with respect to the other, vibrations, chatter, and relative radial movement develop between the joint members despite the presence of the polymeric joint. In most conventional ATVs, the crankshaft bearings are not designed to support additional load or to sustain relative movement, thereby causing damage to the engine and a shorter life for the engine, which are generally inefficient and undesirable. Another drawback of conventional hydraulic pumps, e.g., such as the hydraulic pump disclosed in the ""054 application, the joint mechanism does not allow the drawing of maximum available power from the engine.
Accordingly, a need has developed in the art to provide a hydraulic pump unit that addresses one or more of the drawbacks described above.
It is therefore an aspect of the present invention to provide a hydraulic pump unit that is simple, functional, and inexpensive.
Another aspect of the invention is to provide gears that enable the hydraulic pump unit to increase the available power drawn from the power unit or from the engine.
Another aspect of the invention is to provide a hydraulic pump unit that can be retrofitted to an existing ATV without requiring modification of the ATV or additional engine parts or fittings. For example, the hydraulic pump unit can be mounted on the engine in replacement of an auxiliary starter that would normally be mounted on the engine.
Yet another aspect of the invention is to provide an ATV provided with a hydraulic pump unit as described above.
According to one preferred embodiment of the present invention, an ATV including a frame, a power unit, and a hydraulic pump unit. The power unit is mounted on the frame for propulsion of the ATV. The power unit has an output shaft and a mounting structure. A hydraulic pump unit includes an assembly casing mounted to the mounting structure of the power unit. A hydraulic pump is mounted to the assembly casing. The hydraulic pump has a rotatable input shaft and a shaft extension coupled to the output shaft. The shaft extension is carried by the assembly casing so as to be coaxial with the output shaft. A coupler couples the shaft extension to the input shaft.
In another preferred embodiment of the present invention, a hydraulic pump unit comprises an assembly casing, a hydraulic pump, a shaft extension and a coupler. The assembly casing is adapted to be removably mounted to power unit mounting structure. The hydraulic pump is mounted to the assembly casing and has a rotatable input shaft. The shaft extension is carried by the assembly casing so as to be coaxial with an output shaft of a power unit. The coupler which may be carried by the shaft extension couples the shaft extension to the input shaft.
In yet another preferred embodiment of the present invention, a hydraulic pump unit that is retrofitted onto an ATV, for example, in replacement of an auxiliary starter operatively coupled to the ATV. The hydraulic pump unit comprises a casing having a shaft extension. The shaft extension is provided with a first gear and a hydraulic pump has a second gear that meshes with the first gear. A first coupling member is supported on the shaft extension. A second coupling member has a first end attachable to an engine crankshaft and a second end that is selectively coupleable with the first coupling member. The second coupling member is at least partially supported on the shaft extension.
Because at least a portion of each of the first and second coupling members is carried by the shaft extension such that neither coupling members can move radially relative to the shaft extension, the coupling members are also prevented from moving radially relative to each other. Consequently, the vibrations and relative radial movement that plagued the hydraulic pump assembly disclosed in the ""054 application are prevented in the hydraulic pump unit according to the present invention.
A method of retrofitting a hydraulic pump unit onto an ATV is also provided. The method comprises removing at least a portion of an auxiliary starter to expose an output shaft of the power unit. Providing a hydraulic pump unit including a casing having a shaft extension provided with a first gear and a hydraulic pump having a second gear that meshes with the first gear. Coupling the hydraulic pump unit to the output shaft of the ATV.
These and other aspects of the invention will be described in or apparent from the following detailed description of preferred embodiments.